F. Hebal1, J. Green2, B. Malas1, M. Reynolds1,2 1Ann & Robert H Lurie Children’s Hospital Of Chicago,Pediatric Surgery,Chicago, IL, USA 2Northwestern University,Feinberg School Of Medicine,Chicago, IL, USA
Introduction: Computed tomography (CT) derived Haller Index (HI) is the gold-standard metric of Pectus Excavatum (PE) deformity severity. White Light Scanning (WLS), a novel 3D imaging modality, offers a potential alternative that is quick, inexpensive, and safe. Using no ionization radiation, WLS may be safely used for repeated scanning in longitudinal monitoring of progression of PE deformity. Previous pilot investigation demonstrated feasibility of using a handheld White Light Scanning (WLS) device to measure PE deformity and showed promising early correlation results of a new WLS-derived PE severity index, the Hebal-Malas Index (HMI), with CT-derived HI. Further investigation is necessary to establish WLS-derived HMI as a potential preoperative study modality in PE. This study assesses correlation of HMI with HI measured in preoperative CT scans of pediatric patients with PE.
Methods: We conducted a retrospective review of preoperative CT scans in pediatric patients with PE from 2006-2015. Reported HI was collected from the CT impression documented in the electronic medical record (EMR), and two raters independently measured HI and HMI using this same CT scan. Pearson correlation assessed rater measured HMI with EMR reported HI and rater measured HI. Intraclass Correlation (ICC) assessed interrater reliability of HMI. Measurement and calculation of HMI and HI is shown in Figure 1.
Results:Of 140 identified charts, 35 with incomplete data collected were excluded (18 HI undocumented in record, 8 HMI unmeasurable in scan, 4 no CT image found, 5 incomplete HMI data) leaving 105 for review. For Rater 1 measured HMI, Pearson analysis showed strong correlation with EMR reported HI (r=0.74;p-value<.0001;n=105), Rater 1 measured HI (r=0.77;p-value<.0001;n=105), and Rater 2 measured HI (r=0.71;p-value<.0001;n=41). For Rater 2 measured HMI, Pearson analysis showed moderate correlation with Reported HI (r=0.41;p-value=0.012;n=37), Rater 1 measured HI (r=0.43;p-value=0.008;n=36), and Rater 2 measured HI(r=0.42;p-value=0.009;n=37). To date, complete HMI data for both raters was collected for 36 scans. For these 36 scans, ICC showed strong interrater reliability of HMI between two raters (ICC=0.71;CI:0.501-0.841;P-value<0.0001).
Conclusion:Correlation of HMI with HI and reliability between raters demonstrates strong potential for the use of HMI as a proxy for Haller Index. Currently enrolling prospective investigation of WLS-derived HMI with CT-derived HI continues with the goal of establishing WLS as a preoperative study and progress monitoring modality for patients with PE
